Homogenous cellulose solution and high tenacity lyocell multifilament using the same

ABSTRACT

The present invention relates to a method for making highly homogenized cellulose solution, wherein the cellulose solution is obtained by obtaining a solidified N-methylmorphorine-N-oxide (hereinafter, referred to as ‘NMMO’) hydrates which is solidified a liquid-state NMMO hydrates comprising 10 to 18% by weight water by using a simple screw-type feeder and by controlling the temperature, feeding the solidified NMMO into a twin-screw type extruder continuously, obtaining a cellulose solution which is fully swelled in a few minutes by dispersing and mixing with cellulose powder in the twin-screw type extruder, and extruding a highly homogenized cellulose solution by feeding the obtained cellulose solution into a melting zone of the extruder to melting the cellulose solution in a few minutes by minimum heat and shear force.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of application Ser. No. 10/481,474filed Dec. 18, 2003 which in turn is a U.S. national phase ofPCT/KR03/02251 filed Oct. 24, 2003.

TECHNICAL FIELD

The present invention relates to a manufacturing method for makinghighly homogenized cellulose solution, wherein the cellulose solution isobtained by obtaining a solidified N-methylmorphorine-N-oxide(hereinafter, referred to as ‘NMMO’) hydrates which is solidified aliquid-state NMMO hydrates comprising 10 to 18% by weight water by usinga simple screw-type feeder and by controlling the temperature, feedingthe solidified NMMO into a twin-screw type extruder continuously,obtaining a cellulose solution which is fully swelled in a few minutesby dispersing and mixing with cellulose powder in the twin-screw typeextruder, and extruding a highly homogenized cellulose solution byfeeding the obtained cellulose solution into a melting zone of theextruder to melting the cellulose solution in a few minutes by minimumheat and shear force.

The above cellulose solution can be used to manufacture ancellulose-made article such as fiber, filament, film or tube. Morespecifically, the highly homogenized cellulose solution which isminimized thermal-degradation according to the present invention can beused to manufacture a fiber and the fiber has excellent tenacity anddimensional stability and can be used for making industrial filamentfiber or reinforcing material of rubber-made products such as tire orbelt.

BACKGROUND ART

It has been proposed previously to make cellulose solution using theNMMO hydrates as follows.

U.S. Pat. Nos. 4,142,913, 4,144,080 disclose manufacturing methods formaking cellulose solution by obtaining cellulose solution by underreduced pressure distillation of cellulose that is swelled and dispersedin NMMO hydrates, solidifying the cellulose solution to a precursor(solid-state) by cooling the cellulose solution (a kind if ‘makingchips’) and melting in an extruder. These methods simplify the meltingprocess by using an extruder, but require relatively long time and alarge amount of energy because of the preceding ‘making chips’. Andalso, the precursor is hard to protect from heat and humidity.

U.S. Pat. No. 5,584,919 discloses a manufacturing method for makingcellulose solution by preparing solid-state NMMO comprising 5 to 17% byweight water, feeding the solid-state NMMO with cellulose powder into ahorizontal cylinder-type high speed mixer and mixing them to make agranule type precursor, and melting the precursor using an extruder.This method, however, has a disadvantage of a wide distribution of theobtained the precursor and low yield. If the volume of the raw materialis larger, the distribution of the obtained precursor is more widened.And a complicated cooling apparatus is required to transfer and storethe precursor. And also, the solid-state NMMO is hard to manufacture andstore.

U.S. Pat. Nos. 5,094,690, 5,534,113 and 5,603,883 disclose amanufacturing method for making cellulose solution by dispersingcellulose in the NMMO comprising 40% by weight water to make slurry,removing the water from the slurry by using a Force-drive typethin-layer distillation apparatus that can form a thin, solution-layer,and obtaining the cellulose solution. These methods, however, havedisadvantages of a low efficiency to the volume of the raw materialbecause the slurry was distilled the water and melted by rotating of therotor so slurry was downstreamed. It caused a short dwelling time in theabove apparatus. And also, these methods require a relatively long timeand relatively a large amount of energy to produce cellulose solution,and the obtained fiber using the above cellulose solution gets worse thetenacity by degradation of cellulose and change of color of the NMMO.

U.S. Pat. Nos. 5,421,525, 5,456,748, 5,534,113 and 5,888,288 disclosemanufacturing methods cellulose solution by mixing pulp crashed intoirregular flat type with NMMO comprising 22% by weight water in ahorizontal cylinder-type mixer and swelling them, swelling again bystirring for hours in a storage hopper, removing the water form the highviscid solution by using a Force-drive type thin-layer distillationapparatus so as to obtain the melted cellulose solution. These methods,however, have a disadvantage of extra handling and feeding of dust pulpproduced as by-product during when crash the pulp into irregular flattype pulp. And also, it is hard to operate the horizontal cylinder-typemixer to discharge the swelled solution. In U.S. Pat. No. 5,921,675discloses a horizontal cylinder-type mixer comprising a conveyor screwat the outlet of the mixer.

U.S. Pat. No. 5,948,905 discloses a manufacturing method for makingcellulose solution by distilling the water from a mixture of celluloseand NMMO hydrates comprising about 23% by weight. In this method, themixture was distilled under reduced pressure during passing the nozzlehaving 1.5 to 6.0 millimeter diameter. It is composed of multi-stagechambers. The first-stage chamber has a small number of nozzles havingrelatively large diameter. As the chamber's stage is increased, thenumber of nozzle is increased and the diameter of the hole of the nozzleis decreased so as to increase the cross-sectional area in order toupgrade the efficiency of water vaporization. At the stage of eighth,the last stage, an extruder is used. This method, however, has adisadvantage of needing of a highly complicated apparatus that iscomposed of many chambers different each other and comprised too manyscrews for shifting the chambers and distilling stages.

PCT WO 1997/47790 discloses a manufacturing method for making cellulosesolution by solving cellulose powder in the liquid-state NMMO directlyin a twin-screw type extruder. The cellulose solution is produced byfeeding the liquid-state NMMO comprising 12% by weight water into thefirst barrel of the extruder maintaining an inner temperature of 100°C., feeding cellulose powder into the third barrel of the extrudermaintaining an inner temperature of 75° C., shifting and mixing them,and obtaining the solution by rising the temperature to 120° C. In thismethod, however, three barrel of the extruder is used for feeding thecellulose powder and NMMO, and another barrel is required for meltingthe cellulose. In fact, there is a relatively short swelling zone so asto obtain cellulose solution comprising not-liquified celluloseparticles. So, this method is effective to proceed relatively smallamount of raw material, however, it is not proper to adapt a massproduction of cellulose solution because there are too manynot-liquified moiety. And it is not proper economically because ofrequiring a lot of filter system. And also, this method has adisadvantage of too short spinning cycle. If the swelling zone of theextruder is increased by increasing the number of blocks and theL/D(length/diameter) of the screw, it is hard to control the swellingcondition and the melting condition concurrently because the screws ofthe extruder are driven by single driving shaft.

Korean patent application laid-open publication No. 2002-24689 disclosesa manufacturing method for making highly homogenized cellulose solutionby obtaining a mixture of swelled cellulose pulp powder and liquid-stateNMMO by using the liquid-state NMMO that is overcooled by cooling airand melting the mixture. This method, however, is hard to control thetemperature of the overcooled NMMO by using the cooling air and tocontrol the content of the NMMO because of exposing of the moisturecontained in the cooling air.

After being disclosed in U.S. Pat. No. 2,179,181 granted to Graenacherand Sallman (1939) and the British Patent No. 1,444,080 granted toJohnson tertiary amine oxide as the one of the most powerful solvent forsolving cellulose, there are many patent and literature disclosed theusing of the solvent. And NMMO is the most popular solvent amongtertiary amine oxide. The oxygen of the N—O group, active moiety, of theNMMO can form a inter-molecular linkage with hydroxy group of a materialsuch as cellulose so as to penetrate easily in the crystalline structureof the cellulose. Chanzy et al. subscribed that there are somedifferences of reaction activation according to the extent of hydrationof the NMMO and temperature.

DISCLOSURE OF INVENTION

We, the inventors of the present invention, find out that there are manyfactors that affect to the reaction activation. And, the factors are theconcentration of cellulose, degree of polymerization (DP) of cellulose,a contacting method and apparatus of cellulose and NMMO and the state ofNMMO (liquid-state, solid-state or mid-state thereof) except thetemperature.

As described above, the prior arts provided manufacturing methods formaking cellulose solution by contacting cellulose with NMMO containing20 to 40% by weight water firstly, then, distilling the water by using avariety of distillation apparatus, followed by swelling and melting thecellulose. There are, however, some disadvantages of shifting highviscose solution, equipping an apparatus for dwelling the raw materialsfor the time to distill the water from high viscose solution, anover-sizing of an apparatus for distilling water under reduced pressureand a large amount of energy consuming, etc. And, there is an ideaaccording to the prior arts to manufacture cellulose solution by solvingcellulose powder directly in the liquid-state NMMO comprising about 13%by weight. This method, however, has a disadvantage of remainingnot-liquified moiety that caused by melting the cellulose immediatelywithout swelling when the cellulose contacts with the NMMO maintainingat the temperature of 80° C. (the crystallization temperature of NMMO)or more that has too high reaction activation.

When observing the cellulose fiber of the pulp for solvingmorphologically, the holes (hereinafter, referred to as ‘pit’) thatpenetrate water and the thickness of the cell wall were distributed notuniformly. So, there are some areas that water can penetrate easily andother areas that water can penetrate hardly. And this made somedifferences to penetrate NMMO in the cellulose in a pre-determined time.And, this tendency were showed in case of manufacturing pulp from woodfiber according to the kinds of wood fiber and processes used for makingpulp. Consequently, to obtain fully homogenized cellulose solution, itis required that the solvent is fully penetrate to the cellulose whollyand swelled the cellulose. Otherwise, there remains some not-liquifiedmoiety by not fully melted that caused by regional differences of thesolubilities inter- or intra-fibers of the cellulose fibers.

According to the present invention, twin-screw type extruder is usedthat can swell the cellulose in a relatively short time by forcingexcellent shear force and dispersion force so as to fully and uniformlypenetrate the solvent into the cellulose. In recent, the twin-screw typeextruder has an excellent applicability to the viscose solution andkneading property and easy to control the temperature is used ascontinuous type polycondensation apparatus or depolymerization apparatusin substitute for batch-polymerization system as known.

And the twin-screw type extruder system also can be used for chemicallyreforming apparatus and polymer compounding apparatus. The presentinvention is to provide a manufacturing method for making cellulosesolution by cooling the liquid-state, concentrated NMMO under themelting point of the NMMO to produce firstly solid-state NMMO by usingextra screw system maintaining at relatively low temperature.

According to the present invention, it is characterized that the two rawmaterials are fed into an extruder as solid-state, and then, thecellulose are fully swelled by dispersing, mixing, compressing andshearing, followed by melting the cellulose. It is also possible toproduce a powder type, solid-state NMMO by using a side feeder of thetwin-screw type extruder having narrow pitch screw. It can be uniformlydispersed and mixed with cellulose.

Cellulose solution can be made at relatively low temperature by usinghigh shearing force for 10 minutes or less, and the obtained cellulosesolution that is minimized the degradation of the cellulose and NMMO canbe used to manufacture not only fibers for clothes but also industrialfiber such as tire cord that requires high tenacity.

It is an object of the present invention to provide a manufacturingmethod for making cellulose solution that is homogenized. It is anotherobject of the present invention to provide a manufacturing method formaking lyocell fiber to produce tire cord that has excellent tenacityand modulus in a high productivity.

The foregoing objects and others are accomplished in accordance with thepresent invention, generally speaking, by providing a method for makingcellulose solution, the method comprising steps of: (A) preparingsolid-state NMMO by cooling liquid-state NMMO within a few seconds byusing a side feeder of a twin-screw type extruder, and then, feeding thesolid-state NMMO into the twin-screw type extruder; (B) compressing andfeeding cellulose powder within a few seconds by using side feeder ofthe twin-screw type extruder at the same time of the above step (A); and(C) obtaining cellulose solution swelled and homogenized from thecellulose powder and solid-state NMMO by the twin-screw type extruderhaving a screw to be subjected to dispersing, mixing, shearing,kneading, melting and measuring processes.

It is another object of the present invention to provide cellulose fiberhaving excellent tenacity that is produced by a method comprising a stepof (D) after-treating the obtained multi-filament by washing, drying,oil-treating and winding. The obtained cellulose fiber has someproperties of (1) a tenacity of 5 to 10 g/d, (2) an elongation of 4 to15%, (3) a modulus of 200 to 400 g/d, (4) a birefringence of 0.01 to 0.1and (5) a shrinkage of −0.5 to 5%.

The solid-state NMMO can be obtained by cooling the liquid-state NMMOcomprising 10 to 18% by weight water, and more specifically, about 13%by weight water in substituent for the liquid-state NMMO in the priorart under its melting point by contacting it with a screw maintainingthe temperature of −10 to 80° C. at the steps (A) and (B) of the presentinvention. The obtained, solid-state NMMO powder and cellulose powderare fed into coinstantaneously into a twin-screw type extruder anddispersed, mixed and sheared them in the extruder so as to swell anddisperse them, and, finally, expelled in the form of homogeneouscellulose solution by liquefied in the liquidifying stage.

High tenacity cellulose fiber according to the present invention ismanufactured by feeding solid-state NMMO and cellulose powdercoinstantaneously into a twin-screw type extruder, dispersing, mixingand shearing them in the extruder so as to swell and disperse them,expelling in the form of homogeneous cellulose solution, and spinningthe obtained homogeneous cellulose solution.

It is required to use pulp having a high degree of purity of cellulose.It is known as the lignin having amorphous structure and hemicellulosehaving low crystalline structure. So, to obtain high quality cellulosefibers, it is preferred that the contents of the lignin andhemicellulose be lower and the content of α-cellulose be higher.Cellulose fiber having good physical and chemical properties can beobtained using cellulose molecules that is highly oriented and highlycrystallized by using cellulose having high degree of polymerization.More specifically, it is preferred to use wood pulp that the DP (degreeof polymerization) is 800 to 1,200 and the content of α-cellulose is 93%or more.

According to the present invention, it is characterized in that thesolid-state NMMO is prepared firstly by cooling the liquid-state NMMOcontaining 10 to 18% by weight water, and more specifically, about 13%by weight water in substituent for the liquid-state NMMO in the priorart under its melting point by contacting it with a screw maintainingthe temperature of −10 to 80° C., and more specifically 10 to 50° C. Ifthe temperature of the screw is −10° C. or less, it is not propereconomically because of requiring another barrel to maintain the screwat low temperature, and if the temperature of the screw is 80° C. ormore, the liquid-state NMMO cannot solidified to solid-state NMMO.

According to the present invention, it is preferred to use NMMOcontaining 10 to 18% by weight water in substituent for the liquid-stateNMMO. If the content of water is 10% by weight or less, it is not properto economically because of the cost for concentrating the content ofwater less than 10% by weight, and if the content of water is 18% byweight or more, the solubility is lowered.

In the present invention, the diameter of the cellulose powder using inthe step (A) is not greater than 5,000 micrometer, and morespecifically, not greater than 500 micrometer. If the diameter is 5,000micrometer or more, the solubility of the cellulose is lowered becauseentanglement of the cellulose powder is occurred when solving thecellulose powder.

In the present invention, the content of the cellulose powder in thesolid-state NMMO is in the range of 3 to 20% by weight. If the contentof the cellulose powder is less than 3% by weight, the properties of theobtained cellulose fiber is too lowered, and the content of thecellulose powder is more than 20% by weight, the solubility of thecellulose is lowered.

According to the present invention, the twin-screw type extruder usingin the step (B) to proceed swelling and homogenizing the cellulosepowder and the solid-state NMMO so as to produce a cellulose solutionhas 3 to 16 barrel or 12 to 64 L/D of the screw. If the barrel is lessthan 3 or the L/D of the screw is less than 12, the cellulose solutionexpelled through the barrel is too small so as to produce not-liquifiedmoiety in the solution, and if the barrel is more 16 or the L/D of thescrew is more than 64, the screw of the extruder can be deformed becauseof hard stress acted to the screw.

According to the present invention, the cellulose powder in the step (A)can be mixed with other polymer or additives. Polyvinylalcohol,polyethylene, polyethyleneglycol or polymethylmethacrylate can be usedas the above polymer, and thickner, titanium dioxide, silica (silicondioxide), carbon or ammonium chloride can be used as the additives.

BRIEF DESCRIPTION OF DRAWINGS

Further objects and advantages of the invention can be more fullyunderstood from the following detailed description taken in conjunctionwith the accompanying drawings in which:

FIG. 1 is a scheme of the manufacturing apparatus for making cellulosesolution according to the present invention.

FIG. 2 is a graph illustrating crystalline core forming time versus thesurface temperature of the screw element of the manufacturing apparatusfor making cellulose solution according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is a scheme of the manufacturing apparatus for making cellulosesolution according to the present invention, a pre-concentrated, highconcentration, liquid-state NMMO comprising 10 to 18% by weight water,and more specifically, 12 to 15% by weight water is fed into a inlet (5)by using a fixed quantity-pump, and simultaneously, the liquid-stateNMMO is converted into a solid-state NMMO in a few seconds by using theside feeder (1) of the twin-screw type extruder (3). And, at the sametime, cellulose powder having its diameter not greater than 5,000micrometer is compressed and fed into the twin-screw type extruder (3)continuously by using the side feeder of the twin-screw type extruder.

The cellulose solution swelled and homogenized can be obtained from thesolid-state NMMO and the cellulose powder by the twin-screw typeextruder which is configured a screw to proceed dispersing, mixing,shearing, kneading, melting and measuring. And the manufacturing methodfor making cellulose solution according to the present inventioncharacterized in that the method is carried out by using the twin-screwtype extruder system and the two raw materials were fed into theextruder by using a side feeder continuously and there is not included awater distillation apparatus using extra vacuum apparatus in the system.

FIG. 2 is a graph illustrating crystalline core forming time versus thesurface temperature of the screw element of the manufacturing apparatusfor making cellulose solution according to the present invention, and inorder to measure the time needed for solidifying the liquid-state NMMOto solid-state NMMO, the crystalline core forming time is measured atthe surface temperature of the screw element when the liquid-state NMMOis contacted with the screw element by the thickness of 2 millimeter. Asshown in FIG. 2, when the temperature of the NMMO is 90° C., and thetemperature of the screw element is 30° C. or less, the crystalline coreis formed within 10 seconds.

Hereinafter, the manufacturing method for making cellulose fibercomprising the step of spinning the obtained, homogeneous cellulosesolution, washing, drying and winding is described in detail as follows.The cellulose fiber according to the present invention, however, is notlimited to the cellulose fibers obtained by the following processes.

In the manufacturing method according to the present invention, the (C)step of a spinning step, is carried out by expelling and spinning theobtained dope through a spinning nozzle comprising a number of orifice,and the orifice has 100 to 300 micrometer of diameter, 200 to 2,400micrometer of length, and L/D of 2 to 8 times, and the distance betweenthe orifices is 1.0 to 5.0 millimeter, and solidifying the fiber-shapeddope through an aeration layer and solidifying bath so as to obtainmulti-filament fiber.

The spinning nozzle used in the above has a round shape, and thediameter of the nozzle is in the range of 50 to 200 millimeter, and morespecifically, in the range of 80 to 130 millimeter. If the diameter ofthe nozzle is 50 millimeter or less, it is too short the distancebetween the orifices so the efficiency of cooling is to be lowered andthe fiber-shaped dope is tend to stick each other before they weresolidified, and if the diameter of the nozzle is 200 millimeter or more,the pack for spinning and nozzle are too bulky. Also, diameter of theorifice is 100 micrometer or less, there is a tendency to occur manybreaking-fiber and the spinning efficiency is too low, and if thediameter of the orifice is 300 micrometer or more, the solidifying speedis too late at the solidifying bath and the washing of NMMO is hard. Ifthe length of the orifice of the nozzle is 200 micrometer or less, thedope is not fully oriented so the obtained fiber has a bad property, andif the length of the orifice of the nozzle is 2,400 micrometer or more,it is hard to produce the orifice itself.

It is more preferred to use the nozzle comprising 500 to 2,200, and morespecifically, 700 to 1,400 of the orifice number for making industrialfiber, more specifically, for making tire cord, and for cooling the dopeuniformly. There were some efforts for making lyocell fiber, however,there is no report that high tenacity filament for tire cord wasmanufactured successfully. As the number of filament is increased whenspinning, there are many factors that affect to the efficiency ofspinning and high degree spinning techniques are required.

According to the present invention, to solve the above problems, thespinning nozzle comprising 500 to 2,200 of the orifice number is used.If the number of the orifice is 500 or less, the fineness of eachfilament is too thick to extract the NMMO from the filament in a shorttime so solidifying and washing the filament cannot be enough. And ifthe number of the orifice is 2,200 or more, it is easy to contactbetween the filaments in the area of aeration layer, and after spinning,the stability of each filament is too lowered so as to occur lowering ofproperties of the obtained fiber. Moreover, the obtained fiber is hardto process of twisting thread and heat-treating for producing tire cord.

When the dope passed the spinning nozzle is conjugated in the upperconjugation bath, the filament formed from the dope is too thick, thedifferences of the conjugation speed between the surface and inner partso that the fiber having fine and uniform texture hardly can obtained.Therefore, in case of the same amount of dope is spinning, the filamentcan be fed into the conjugation bath maintaining more thin diameter bycontrolling the aeration layer properly. If the air-gap (length of theaeration layer) is too short, it is hard to increasing the ratio ofdrawing because of rapid surface-solidifying, increasing the ratio ofmicropores-forming during desolventation, and these makes hard toincrease the ratio of drawing of the filament and also hard to increasethe speed of the spinning for making filament. Contrary, if the air-gapis too long, it is hard to maintain the stability of the processingbecause of adhering between filaments and influences of ambienttemperature and humidity.

The air-gap is 10 to 200 millimeter, and more specifically, 20 to 100millimeter. When the filament is passing the air-gap, cool air can befed in order to preventing adhering between filaments by cooling andsolidifying the filament, and at the same time, increasing thepenetration resistance to the solidifying solution. The cool air can becontrolled by monitoring the temperature and humidity of the air by asensor located between the inlet of the cooling air supplying means andfilament. The temperature of the air can be controlled in the range of 5to 30° C. If the temperature of the air is 5° C. or less, thesolidification of the filament is too rapid so high-speed spinning ishard to proceed, and also it is not proper economically because ofovercooling the air. Contrary, if the temperature of the air is 30° C.or more, the penetration resistance of the dope to the, solidifyingsolution is too lowered so breaking-fiber can be occurred.

Also, the content of the water in the air is one of the most importantfactors and it can affect the solidifying of the filament. It ispreferred to control the relative humidity in the range of 10 to 50% RH.More specifically, it is preferred to provide dry air controlled to therelative humidity in the range of 10 to 30% RH to the surroundings ofthe nozzle, and wet air controlled to the relative humidity in the rangeof 30 to 50% RH to the surroundings on the solidifying solution in orderto increase the stabilities of the speed of solidifying of the filamentand sticking at the surface of the nozzle. It is preferred to blow thecooling air horizontally to the side face of the filament that expelleddownwardly. It is preferred to control the speed of the cooling air inthe range of 0.5 to 10 m/second, and more specifically, in the range of1 to 7 m/sec. If the speed of the cooling air is too slow, the coolingair cannot prevent the other conditions of ambient atmosphere, and it ishard to obtain uniform filament because there are some differences ofsolidifying speed in the area contacting with the cooling air at thelatest and breaking-fiber. Otherwise, if the speed of the cooling air istoo fast, the spinning efficiency is too low, caused by swinging thecourse of the filament, adhering between filaments and preventinguniform flowing of the dope.

The composition of the solidifying solution used in the presentinvention is 5 to 40% by weight of aqueous NMMO solution. When thefilament passing the conjugation bath, the speed of spinning is 50m/minute or more, the shaking of the conjugation solution will beextreamed by the friction between the filament and the conjugationsolution. In order to increase the productivity by increasing the speedof spinning and to achieving excellent properties through elongation andorientation, it is required to minimize these phenomena because thesephenomena can affect to the stability of the processing.

In the step (D) according to the present invention, the obtained multifilaments are introduced into the washing bath, and washed them. As adesolventation and elongation that can affect the properties of thefilament greatly were occurred constantly during passing the solidifyingbath, the temperature and concentration of the solidifying solutionshould be maintained constantly. The filament that passed out thesolidifying bath washed in the washing bath. The washing method is wellknown to the ordinary skilled technical expert in the art.

The washed filament, then, dried and oil-treated, followed by winded.Drying, oil-treating and winding processes are well known to theordinary skilled technical expert in the art. Then, the obtainedfilament can be used for manufacturing of tire or industrial filament.

The obtained lyocell multi filaments according to the present inventionhave 1,000 to 3,500 of total deniers and 8.0 to 18.0 kilogram of cuttingload. The multi filaments comprise 500 to 2,200 of filament, and eachfilament has a fineness of 0.5 to 4.0 deniers. The filament also has atenacity of 5.0 to 10 g/d, an elongation ratio of 4 to 10%, anelongation ratio at 4.5 kilogram load of 0.5 to 4.0%, a modulus of 200to 400 g/d, birefringency of 0.030 to 0.060, a shrinkage of −0.5 to 3%.So, the filament is useful to manufacture a tire cord of automobile.

High tenacity cellulose fiber according to the present invention can beobtained by providing solid-state NMMO by solidifying liquid-state NMMOin a few seconds using a side feeder of a twin-screw type extruder,feeding the solid-state NMMO into the twin-screw type extruder,compressing cellulose powder in a few seconds using the side feeder ofthe twin-screw type extruder and feeding it into the extruder so as todisperse and mix them each other, shearing them to convert them intohomogeneous cellulose solution which swelled and dispersed and spinningthe dope (the homogeneous cellulose solution).

Raw cord for tire of automobile is manufactured from the obtainedlyocell multi filament by twisting the two strands of filament using adirect twist machine which can twisting at the same time. Two strands ofthe obtained yarns were plied and cabled, and then, twist and add twostrands of filaments to prepare a cord yarn. Generally, the degree ofplying and cabling are the same. That can be possible to maintain theobtained tire cord in straight state without rotation or entanglement.And the properties such as tenacity, elongation, mid-elongation, thedegree of anti-fatigue can be changed according to the degree oftwisting. Generally speaking, if the degree of twisting is increased,the tenacity is lowered, elongation at cutting are increased. And, ithas a tendency to increase the degree of anti-fatigue. According to thedegree of twisting.

Thus obtained raw cord can be weaved using high speed weaving machine.And the obtained textile is dipped into a dipping solution, and then,stiffened to produce a ‘dip cord’ for tire of automobile that iscomposed of the resin-coated on the surface of the raw cord. Dipping isproceeded by wetting the textile with a solution of RFL composition(resorcinol-formaline-latex composition). This is for reinforcing theadhesive property because of the raw cord. Generally, layon or nylon isproceeded by one-pot dipping. But, in case of PET fiber, it is proceededby two-pots dipping, wherein, the PET fiber is activated, and then,reinforced the adhesive property because the PET fiber has fewerreactive group than the layon fiber or nylon fiber. The lyocell multifilaments according to the present invention are proceeded by one-potdipping. And the dipping solution for dipping tire cord is well known tothe ordinary skilled technical expert in the art.

The thus obtained dip cord according to the present invention has 2,000to 8,000 of total deniers and 12.0 to 28.0 kilogram of cutting load. Andit can be used preferably for a tire cord of automobile.

Hereinafter, the present invention is described in detail withreferenced to the following examples, but it is to be understood thatthe examples is solely for the purpose of illustration and do not limitthe scope of the present invention. In the following examples, theestimating method and the measuring method as following is used.

(a) Quality Evaluation of Cellulose Solution

Quality evaluation of cellulose solution used in the examples isevaluated using a microscope (*1,000 magnification, made by Mitutoyocompany) and a evaluation apparatus (Video copy processor SCT-P66, madeby Mitsubishi company, Hi-Scope compact Micro Vision System KH-2200,made by Sharp company). It is declared by the number of not-liquifiedmoiety in the area of 1 centimeter square, and classified into 5 grades.Samples are tested by three times and calculated the mean value. Underthe grade of fourth is accounted as not homogenized solution, and thegrade of third is accounted not fully swelled because of many factors.So, it is preferred to control all of the factors of the solutionmanufacturing apparatus that can affect to the property of the filamentso as to obtain the grade of second as possible. The number ofnot-liquified cellulose powder/cm² Grade   0˜3.5 1 3.6˜7.0 2  7.1˜10.5 310.6˜13.0 4(cannot use for dope) More than 13.1 5(cannot use for dope)(b) Degree of Polymerization (DPw)

The intrinsic viscosity [IV] of the dissolved cellulose is measured asfollows. 0.5M cupriethylenediamine hydroxide solution in the range of0.1 to 0.6 g/dl concentration obtained according to ASTM D539-51T ismeasured by using an Uberod viscometer at 25±0.01° C. The intrinsicviscosity is calculated from the specific viscosity by using thecalculation method of extrapolation and then Mark-Hauwink's equation toobtain the degree of polymerization.[IV]=0.98×10⁻² DP _(w) ^(0.9)(c) Birefingency

Birefringency is measured using Berek compensator as a polarizationmicroscope that the light source is Na-D.

(d) Tenacity (kgf) and Elongation at Specific Load (%)

The tenacity of the filament is measured using low speed elongationtester, and the filament is tested after being dried at 107° C. for 2hours. The filament is twisted by 80 Tpm (80 turns/meter) and the lengthof the filament is 250 millimeter and the elongation speed is 300 m/min.The elongation at specific load is the degree of elongation at 4.5kilogram load.

(e) Shrinkage %

The shrinkage is represented the ratio of the length (L0) measured at 20g static load after being treated at 25° C., 65% RH for 24 hours to thelength (L1) measured at 30 g static load after being treated at 30° C.for 30 minutes.S(%)=(L ₀ −L ₁)/L ₀×100(f) E-S

The elongation (E) means the elongation at specific load (EASL) in thepresent invention, and in this the specific load is 4.5 kilogram load.The specific load of 4.5 kilogram load means the maximum load acted toeach tire cord. And ‘S’ means the shrinkage of the above item (d). Thesum of the elongation (E) and shrinkage (S) and represents as ‘E-S’ inthe present invention. Generally, the tire is vulcanized, the shrinkageand the elongation of the cord is changed. The sum of the elongation (E)and shrinkage(S), ‘E-S’ is similar to the modulus of the tire obtained.That is, if the value of ‘E-S’ is lowered, the modulus is raised. Themodulus is raised, the operation property of the vehicle can be easybecause the amount of force forming according to the transformation ofthe tire. Contrary, in case of the same extent of tension is required,it is possible to the small transformation of the tire. It means theoperation property of the vehicle is good, and the stability of theshape of the tire is also good. So, the above value of ‘E-S’ is utilizedto estimate the property of the tire. And, when manufacturing a tire,the cord having the low ‘E-S’ value can be used effectively because thedeformation of the tire is low. So, it is possible to obtain good andmorphologically uniform tire. And also, it is possible to obtain a tirehaving good property in case of using the low ‘E-S’ value cord incomparison with the case of using the high ‘E-S’ value.E-S=elongation(Elongation at 4.5 kg)+shrinkage

EXAMPLE 1

The cellulose powder is obtained by crashing pulp (DPw(degree ofpolymerization) of 1,200, made by Buckey company, alpha-cellulosecontents of 97%) into powder having 100 micrometer or less diameter. Andthe cellulose powder is fed into an extruder at the speed of 1.2kilogram/hour continuously. And at the same time, the NMMO hydratecomprising 13.5% by weight water at 90° C. is fed into the extruderusing a fixed quantity-pump at the speed of 8.9 kilogram/hourcontinuously. In this time, the side feeder for feeding the NMMO ismaintained at the temperature of 30° C. to 60° C. The screw of thetwin-screw type extruder is rotated at the speed of 200 rpm, and thetemperature of the region between the raw material feeding part andkneading part is maintained at the temperature in the range of 50 to 80°C. The cellulose powder and the solid-state NMMO is fed into theextruder and they are mixed, sheared and kneaded in the extruder so asto produce liquid-state cellulose solution. The concentration of theobtained cellulose solution (dope) is 11.5%. The properties of theobtained cellulose solution are shown in Table 1.

EXAMPLE 2

Another dope (cellulose solution) is prepared as described in Example 1without the temperature of the region between the raw material feedingpart and kneading part is maintained in the range of 50 to 110° C., soas to maintain the temperature of the kneading part more higher incomparison with that of the Example 1. The properties of the obtainedcellulose solution are shown in Table 1.

EXAMPLE 3

Another dope (cellulose solution) is prepared as described in Example 2without the content of the water in the liquid-state NMMO is controlledto 10% by weight. The properties of the obtained cellulose solution areshown in Table 1.

COMPARATIVE EXAMPLE 1

The cellulose powder is obtained by crashing pulp (DPw of 1,200, made byBuckey company, alpha-cellulose contents of 97%) into powder having 100micrometer or less diameter. And the cellulose powder is fed into anextruder at the speed of 1.2 kilogram/hour continuously. And at the sametime, the NMMO hydrate comprising 13.5% by weight water at 90° C. is fedinto the extruder using a fixed quantity-pump at the speed of 8.9kilogram/hour continuously. In this time, the screw of the twin-screwtype extruder is rotated at the speed of 200 rpm, and the temperature ofthe region between the raw material feeding part and kneading part ismaintained at the temperature in the range of 50 to 80° C. The cellulosepowder and the solid-state NMMO is fed into the extruder and they aremixed, sheared and kneaded in the extruder so as to produce liquid-statecellulose solution. The concentration of the obtained cellulose solution(dope) is 11.5%. The properties of the obtained cellulose solution areshown in Table 1. TABLE 1 EXAM- EXAM- EXAM- COMPARATIVE PLE 1 PLE 2 PLE3 EXAMPLE 1 The number of not- 0.3 7.2 10.8 12.4 liquified particle/cm²The fraction of pack 3.2 5.5 15.3 20.4 pressure rising(ΔP)/day (kg/cm²)Grade 1 3 4 4

EXAMPLE 4

Another dope (cellulose solution) is prepared as described in Example 1.The spinning nozzles having their diameter of 120 millimeter and thenumber of orifice of each nozzle of 800, 1,000, 1,200 are used tomanufacture the cellulose solution. The diameter of the orifice is 150micrometer. L/D(length per diameter) of the orifice are all 4. The dopeexpelled from the spinning nozzle (head temperature of 110° C.) areaerated in the aeration layer apart from the nozzle with cooling airhaving the temperature of 20° C. and relative humidity of 40% RH at thespeed of 4 m/sec. And, other conditions such as spinning amount and thespeed of spinning are regulated to obtain multi filament having thefinal fineness of 1,500 to 2,000 deniers. The solidifying bath isregulated to the conditions that the temperature of the solidifyingsolution is 20° C. and the composition of the solidifying solution is20% by weight NMMO and 80% by weight water. And, at that time, thecooling air and the solidifying solution are monitored using a sensorand a refractometer continuously. The remaining NMMO in the obtainedfilament withdrawn from the solidifying bath is removed by washing them.And then, the obtained filament are dried and winded. The properties ofthe obtained filament are shown in Table 2. TABLE 2 EXAMPLE 4 A-1 A-2A-3 A-4 A-5 Condition Diameter of the 120 120 120 120 120 nozzle(mm)Number of the 800 1000 1200 1000 1000 nozzle orifice Diameter of the 150150 150 150 150 nozzle orifice(μm) Filament denier 1510 1508 1502 17202004 Property of the filament Tenacity(g/d) 7.6 7.7 8.5 7.0 6.0 EASL(%)1.1 1.0 1.1 1.3 1.4 Elongation at 5.6 5.3 4.9 5.6 5.7 break(%)Modulus(g/d) 307 310 330 290 271 Birefringence 0.044 0.045 0.049 0.0430.041 Shrinkage 0.4 0.5 0.2 0.8 1.2

There are no problems according to the number of orifice. As increasethe number of the orifice, the tenacity also increased and themid-elongation and elongation at cutting are lowered in the viewpoint ofthe properties. In the viewpoint of the modulus, the modulus is highestin case of the number of the orifice is 1,200. In case of the finenessof the filament is controlled in the range of 1,500 to 2,000 deniers bycontrolling the amount of spinning and the speed of spinning, there areno problems in the viewpoint of the stickiness to the nozzle.

And, as increase the filament's deniers, the tenacity is decreased andthe elongation is increased in the viewpoint of properties.

EXAMPLE 5

After another dope (cellulose solution) is prepared as described inExample 2, filament fiber is prepared as described in Example 4. Theproperties of the obtained filament are shown in Table 3. TABLE 3EXAMPLE 5 A-1 A-2 A-3 A-4 A-5 Condition Diameter of the 120 120 120 120120 nozzle(mm) Number of the 800 1000 1200 1000 1000 nozzle orificeDiameter of the 150 150 150 150 150 nozzle orifice(μm) Filament denier1510 1508 1502 1720 2004 Property of the filament Tenacity(g/d) 7.6 7.78.5 7.1 6.1 EASL(%) 1.1 1.0 1.1 1.3 1.4 Elongation at 5.6 5.3 4.9 5.65.7 break(%) Modulus(g/d) 307 310 330 298 271 Birefringence 0.044 0.0450.050 0.043 0.041 Shrinkage 0.4 0.5 0.2 0.8 1.1

The third grade of cellulose solution has almost no influence to thespinning properties, but the properties of the obtained fiber islowered.

EXAMPLE 6

After another dope (cellulose solution) is prepared as described inExample 3, filament fiber is prepared as described in Example 4. Theproperties of the obtained filament are shown in Table 4. TABLE 4EXAMPLE 6 A-1 A-2 A-3 A-4 A-5 Condition Diameter of the 120 120 120 120120 nozzle(mm) Number of the 800 1000 1200 1000 1000 nozzle orificeDiameter of the 150 150 150 150 150 nozzle orifice(μm) Filament denier1510 1508 1502 1720 2004 Property of the filament Tenacity(g/d) 7.6 7.78.6 7.0 6.3 EASL(%) 1.1 1.0 1.1 1.3 1.4 Elongation at 5.6 5.3 4.9 5.65.7 break(%) Modulus(g/d) 307 310 330 290 270 Birefringence 0.044 0.0450.049 0.043 0.041 Shrinkage 0.4 0.5 0.2 0.8 0.9

In case of the fourth grade of cellulose fiber is used, the spinningproperties and the properties of the obtained fiber is lowered.

COMPARATIVE EXAMPLE 2

After another dope (cellulose solution) is prepared as described inComparative example 1, filament fiber is prepared as described inExample 4. The properties of the obtained filament are shown in Table 5.TABLE 5 COMPARATIVE EXAMPLE 2 A-1 A-2 A-3 A-4 A-5 Condition Diameter ofthe 120 120 120 120 120 nozzle(mm) Number of the 800 1000 1200 1000 1000nozzle orifice Diameter of the 150 150 150 150 150 nozzle orifice(μm)Filament denier 1510 1508 1502 1720 2004 Property of the filamentTenacity(g/d) 5.6 5.7 6.1 4.9 4.5 EASL(%) 1.1 1.0 1.1 1.3 1.4 Elongationat 5.6 5.3 4.7 5.6 5.7 break(%) Modulus(g/d) 283 287 300 247 245Birefringence 0.041 0.042 0.045 0.041 0.039 Shrinkage 0.6 0.7 0.4 0.92.3

In case of the relative example 2, the tenacity is too low and cannot beused to manufacture a tire. And in case of the fineness is 2,300deniers, it is required to use more cord than a proper amount of cord tomake a tire.

INDUSTRIAL APPLICABILITY

According to the present invention, there is provided homogeneouscellulose solution that minimized thermal-degradation. The cellulosesolution can be used to produce a cellulose-made article such as fiber,filament, film or tube, etc. More specifically, the fiber manufacturedby using the above cellulose solution is excellent in tenacity anddimensional stability and may be used for making industrial filamentfiber or reinforcing material of rubber-made products such as tire orbelt.

While the present invention has been described with reference to theparticular illustrative embodiments, it is not to be restricted by theembodiments but only by the appended claims. It is to be appreciatedthat those skilled in the art can change or modify the embodimentswithout departing from the scope and spirit of the present invention.

1. A cellulose article extruded from a solution prepared continuouslyusing a mixture of N-methylmorphorine-N-oxide (NMMO) and water, by: (A)preparing solid-state NMMO by cooling liquid-state NMMO within a fewseconds by using a side feeder of a twin-screw type extruder, and then,feeding the solid-state NMMO into the twin-screw type extruder; (B)compressing and feeding cellulose powder within a few seconds by usingside feeder of the twin-screw type extruder at the same time of theabove step (A); and (C) obtaining cellulose solution swelled andhomogenized from the cellulose powder and solid-state NMMO by thetwin-screw type extruder having a screw to be subjected dispersing,mixing, shearing, kneading, melting and measuring processes. 2.-9.(canceled)
 10. A cellulose fiber manufactured by a method comprising thesteps of: (A) preparing solid-phase NMMO by cooling liquid-phase NMMOwithin 1 to 60 seconds by using a side feeder of a twin-screw typeextruder, and then, feeding the solid-phase NMMO into the twin-screwtype extruder, and simultaneously compressing and feeding cellulosepowder within a few seconds by using side feeder of the twin-screw typeextruder; (B) obtaining cellulose solution swelled and homogenized fromthe fed cellulose powder and solid-phase NMMO by the twin-screw typeextruder with a screw to perform dispersing, mixing, kneading, meltingand measuring, (C) expelling and spinning the cellulose solution througha spinning nozzle, and solidifying it through an aeration layer and asolidifying bath so as to obtain multi-filament; and (D) after-treatingthe obtained multi-filament through washing, drying, oil-treating andwinding; and wherein the cellulose fiber having some properties of (1) atenacity of 5 to 10 g/d, (2) an elongation of 4 to 15%, (3) a modulus of150 to 400 g/d, (4) a birefringence of 0.01 to 0.1 and (5) a shrinkageof −0.5 to 5%.
 11. The cellulose fiber of claim 10, which has a tenacityof 7 to 9 g/d.
 12. The cellulose fiber of claim 10, which has anelongation of 5 to 10%.
 13. The cellulose fiber of claim 10, which hasfilament of 500 to
 2200. 14. The cellulose fiber of claim 10, which hasa total fineness of 250 to 4500 denier.
 15. The cellulose fiber of claim10, which has a monofilament fineness of 0.5 to 4 denier.
 16. Thecellulose fiber of claim 10, which has a shrinkage of −0.5 to 1.5%. 17.The cellulose fiber of claim 10, which has a modulus of 200 to
 350. 18.The cellulose fiber of claim 10, the sum of the mid-elongation (%) andshrinkage (%) is less than 1 to
 4. 19. A tire cord obtained by using thecellulose fiber produced according to claim
 10. 20. A tire obtained byusing the cellulose fiber produced according to claim
 10. 21. Beltproducts obtained by using the cellulose fiber produced according toclaim
 10. 22. Hose products obtained by using the cellulose fiberproduced according to claim 10.